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The present invention relates to integrated circuit sockets and more specifically, to a method for mounting a contact assembly to a frame member of a socket assembly.
Sockets are known for integrated circuits that such as land grid array (LGA) integrated circuit devices. An LGA integrated circuit device typically has a rectangular housing or body and an array of contacts on the bottom surface of the housing arranged in a predetermined contact pattern. These contacts are mateable with contacts of the LGA socket when the integrated circuit device is disposed within the socket.
During the manufacture of the sockets for LGA devices it is necessary to be able to securely mount a contact assembly to the supporting frame. It would be desireable to have be able to securely mount the contact assembly to the frame in a manner that is conducive to the use of high speed manufacturing machinery to permit high volume manufacture of integrated circuit sockets.
In accordance with the present invention, a method for mounting a contact assembly to a frame to form an LGA integrated circuit socket assembly is disclosed. A plurality of posts are integrally formed with and extend from the bottom surface of the frame of the integrated circuit socket in a predetermined post pattern. A contact assembly is provided that includes an insulating sheet having a plurality of apertures arranged in a predetermined contact pattern corresponding to a contact pattern on the underside of an LGA integrated circuit device. A plurality of conductive columns are mounted within the apertures of the insulating sheet. The insulating sheet includes a plurality of post receiving apertures arranged in the predetermined post pattern such that the upstanding posts extend through the post receiving apertures when the insulating sheet is aligned in a mounting position with respect to the frame. To retain the contact assembly in assembled relation with respect to the frame, the insulating sheet is aligned and positioned on the frame such that the posts extend through the post receiving apertures of the insulating sheet. The ends of the posts are then cold staked in increase the diameter of the posts and to form a post head that fixably mounts the insulating sheet to the frame within the socket assembly.
Integrally formed spacer abutments are provided on the underside of the frame to space the bottom surface of the frame a predetermined height above a printed circuit board when the socket assembly is mounted to the printed circuit board. The distance from the bottom surface of the frame to the top of the posts following the cold staking operation is less than the predetermined height of the spacer abutments to assure that the socket assembly is maintained at the proper height with respect to the printed circuit board and thus maintain proper contact forces between the lower end of the conductive columns and corresponding conductive pads on the printed circuit board. In the foregoing manner adhesives need not be employed in the manufacturing process and the LGA integrated circuit sockets may be manufactured using high speed assembly equipment.